High-resolution transient electromagnetic data hybrid dimensional detection method of water hazard in coal mine dataset

Transient electromagnetic method (TEM) surveys in engineering geophysics research can be used to detect low-resistivity target bodies such as water. In this study, we developed a hybrid-dimensional TEM data inversion method that achieves fast and stable 3D inversion results. The newly developed method produces high-resolution coal mine water hazard detection results, which solves the problem of misestimating water hazard anomalies. This method first constructs an initial model reflecting the main electrical structure of the survey region. Then, 3D inversion with the initial model is designed to obtain a precise resistivity model subsurface that can reflect the distribution of water hazards. The initial model is constructed by weighted layered constraint inversion (WLCI) to obtain a reliable subsurface resistivity model of sedimentary strata in coal mines. In addition, as we use unstructured tetrahedral meshes for model discretization, the improved 3D inversion method can effectively eliminate the influence of high-relief topography and improve the positioning accuracy of anomalous bodies. The application of the synthetic model shows that hybrid-dimensional inversion can achieve accurate identification of water hazard-prone geological bodies from reliably restored electrical distributions underground. Field data processing results show that the detection of water in a goaf is effective in a coal mine in Ordos, Inner Mongolia, China. The resistivity distributions of sedimentary strata can be accurately restored by the new method, which fits well with the known geology and underground drilling.

在工程地球物理学研究中，瞬态电磁法（TEM）调查可用于探测低电阻率目标体，如水体。在本研究中，我们开发了一种混合维度的TEM数据反演方法，该方法实现了快速且稳定的3D反演结果。新开发的方法能够产生高分辨率的煤矿水害探测结果，解决了水害异常误估的问题。该方法首先构建了一个反映调查区域主要电结构的初始模型。然后，设计3D反演与初始模型相结合，以获得能够反映水害分布的精确地下电阻率模型。初始模型通过加权层状约束反演（WLCI）构建，以获取煤矿沉积层可靠的地下电阻率模型。此外，由于我们使用非结构化四面体网格进行模型离散化，改进的3D反演方法可以有效消除高起伏地形的影响，并提高异常体的定位精度。合成模型的应用表明，混合维度反演可以从地下可靠恢复的电分布中准确识别出水害易发地质体。现场数据处理结果显示，在内蒙古鄂尔多斯的一个煤矿中，该新方法对采空区中水的探测是有效的。新方法可以精确恢复沉积层的电阻率分布，与已知的地质和地下钻探结果相吻合。